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Description of problem:
When I do test on s390x machine, the console printed following messages:
--------------------------------
ibm-z10-25 login:
01: HCPGSP2627I The virtual machine is placed in CP mode due to a SIGP initial C
PU reset from CPU 00.
cpu: Processor 1 started, address 0, identification 32C5C2
01: HCPGSP2629I The virtual machine is placed in CP mode due to a SIGP stop from
CPU 01.
cpu: Processor 1 stopped
-------------------------
the same console output when I do "echo 1 > /sys/devices/system/cpu/cpu1/online"
Version-Release number of selected component (if applicable):
2.6.32-118
How reproducible:
always
Steps to Reproduce:
1. install RHEL6.1-20110224.2 on s390x machine
2. run some test, eg, /kernel/power-management/gettimeofday
3.
Actual results:
above console output is printed, and cpu1 can not be up.
Expected results:
Additional info:
installed an older kernel 2.6.32-94, the same result.
Comment 5Hendrik Brueckner
2011-03-23 15:48:55 UTC
With RHEL6.0, a program called "cpuplugd" manages the available CPUs depending on the work load of the system. The cpuplug daemon is enabled by default. Whenever a CPUs is switched online/offline, you can see a message with ID "HCPGSP2629I". This is an information message from the z/VM control program (CP).
If the system is idle, the cpuplugd switches off additional CPUs, for example, to reduce z/CM CP scheduling efforts. It also allows to run with a certain overcommitment.
Regarding your issue, if you manually switch an CPU online, cpuplugd will turn it offline on the next check interval.
For your tests, you can stop cpuplugd with "/etc/init.d/cpuplugd stop", or you can use chkconfig to switch off cpuplugd permanently.